Elvis provides a different take on Rove’s resurrection:

If you look at the polls, the collapse in Congress’s approval rating is due to extremely low levels of support among Democrats, around 19 percent as of a few weeks back. By contrast, over half of Republicans still give favorable ratings to the president.
Congress is in trouble because it has failed to stand up to the president on war escalation and, now, on FISA.
Also, the GOP in the Senate is filibustering at a record-shattering pace– they are on target to filibuster three times as often as any Senate session in American history.

In other words, Dems are ticked because they aren’t doing more but certainly don’t want Republicans taking their place. That is what is making their number low. Bush’s number is high simply because R’s are still fairly loyal to him. If this is all true it will just make Rove’s resurrection all the more stunning.